Sammendrag
Impacts of anthropogenic activities on coastal
seabirds might be extensive, especially in the breeding season.
Identifying important foraging areas and associated
habitats is important for a proper management of seabirds.
To identify habitat characteristics driving the selection of
foraging sites of breeding European shags Phalacrocorax
aristotelis, this study used tracking data (GPS- and TDRloggers),
from 282 individual birds comprising 905 foraging
trips and 27,303 dives with known locations, to create habitat
selection models. To explore possible effects of regional
differences in habitat on foraging behavior, the study was
performed at two Norwegian colonies, Sklinna in the Norwegian
Sea (65°N, 11°E) and Hornøya in the Barents Sea
(70°N, 31°E), with distinct differences in seascape structure
and habitat availability. Shags at Sklinna foraged further
away from the colony than those at Hornøya but diving
depth and duration were similar at the two colonies. In both
colonies, sea depth was an important predictor of habitats
selected by chick-rearing shags during foraging, with birds
preferring shallow depths. At Sklinna, shags also selected
for flat areas with high probability of kelp forest occurrence.
There was no difference in trip length and duration between
sexes, but males dived deeper than females in both colonies.
This suggests that males and females might utilize different
microhabitats within the same foraging area. The study
discusses the application of habitat selection modeling to
identify important foraging areas for coastal seabirds, and
how this may contribute to the management, conservation
and assessment of impacts of human activities.
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